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991.
Distance algorithms are most frequently used in robotics to determine the distance between two obstacles in the environment of a robot or between a sensor point and an object. We extend the multibody simulation package MOBILE for an application of accurate algorithms for distance computation between objects represented by convex or non-convex polyhedra. These objects are represented by their vertices and oriented facets. As an application example, a multibody system is discussed where a sensor point moves close to a non-convex obstacle. The computed results show that the algorithms developed are suitable for accurate real-time multibody simulations. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
992.
993.
Klaus Eckart Max C. Holthausen Wolfram Koch Joachim Spiess 《Journal of the American Society for Mass Spectrometry》1998,9(10):1002-1011
B ions represent an important type of fragment ions derived from protonated peptides by cleavage of an amide bond with N-terminal charge retention. Such species have also been discussed as key intermediates during cyclic peptide fragmentation. Detailed structural information on such ion types can facilitate the interpretation of multiple step fragmentations such as the formation of inner chain fragments from linear peptides or the fragmentation of cyclic peptides. The structure of different b2 ion isomers was investigated with collision-induced dissociations (CID) in combination with hydrogen/deuterium (H/D) exchange of the acidic protons. Special care was taken to investigate fragment ions derived from pure gas-phase processes. Structures deduced from the results of the CID analysis were compared with structures predicted on the basis of quantum chemical density functional theory (DFT) calculations to be most stable. The results pointed to different types of structures for b2 ion isomers of complementary amino acid sequences. Either the protonated oxazolone structure or the N-terminally protonated immonium ion structure were proposed on the basis of the CID results and the DFT calculations. In addition, the analysis of different selectively N-alkylated peptide analogs revealed mechanistic details of the processes generating b ions. 相似文献
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995.
Nils Wiberg Wolfgang Niedermayer Hans‐Wolfram Lerner Michael Bolte 《无机化学与普通化学杂志》2001,627(5):1043-1047
Disupersilylsilanides M(SiHR*2)2 of Metals of the Zinc Group (M = Zn, Cd, Hg; R* = Si t Bu3): Syntheses, Characterization, and Structures Bis(disupersilyl)silylmetals M(SiHR )2 (R* = Supersilyl = SitBu3) with M = Zn, Cd, Hg are obtained in tetrahydrofuran/benzene/pentane by the reaction of NaSiHR with ZnCl2, CdI2, HgCl2 in the molar ratio 2 : 1. The compounds form colorless, in organic media soluble, not hydrolysis‐ and air‐sensitive crystals, the stabilities of which for thermolysis or photolysis decrease in the row Zn > Hg > Cd compound. According to X‐ray structure analyses, the compounds M(SiHR )2 are monomeric with a – to date not observed – non‐linear framework –M– (angle SiMSi for M(SiHR )2 with M = Zn/Cd/Hg 170.7/174.2/174.4°). 相似文献
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998.
Wolfram Uhlig 《先进技术聚合物》1999,10(8):573-522
Novel poly(silylenemethylene)s have been prepared by the ring‐opening polymerization of 1,3‐disilacyclobutanes followed by a protodesilylation reaction with triflic acid. The silicon–aryl bond cleavage could be controlled by using different leaving groups, for instance phenyl‐ and para‐anisyl substituents. The reactions of the triflate derivatives with organomagnesium compounds, LiAlH4, amines or alcohols gave functional substituted poly(silylenemethylene)s. Hydrosilylation reactions or reductive coupling with potassium–graphite led to organosilicon network‐polymers, which may serve as suitable precursors for silicon carbide and Si/C/N‐based materials. The structures of the polymers were identified by nuclear magnetic resonance spectroscopy (29Si, 13C, 1H). Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
999.
Wolfram Koch 《Nachrichten aus der Chemie》1999,47(2):103-103
1000.